Self energizing valve means for fluid translating device

ABSTRACT

A self energizing valve for use in controlling the flow of fluid to a fluid translating device having inner and outer members cooperating to define an annular space and being relatively rotatable by flowing fluid through a plurality of passageways communicating with the annular space. The self energizing valve slides in a valve bore and is automatically maintained in a first position by the pressure of fluid flowing through a fluid passage in the valve communicating with the passageways. The valve and bore cooperate to define a cavity and the fluid passage is connectable to the cavity and the pressure of the fluid in the cavity will move the valve from the first position.

United States Patent 1191 Wilcox July 24, 1973 [54] SELF ENERGIZINGVALVE MEANS FOR 7 3,639,093 2/1972 Jansson 418/177 FLUID TRANSLATINGDEVICE P E w I F h nmary xammer-- 1 1am ree [75] inventor. John PWilcox, Columbus, 01110 Assistant Emmi-MP4,) winbum [73] Assignee: J. I.Case Company, Racine, Wis. At orney-Max Dressler et al' [22] Filed: July21, 1971 [57] ABSTRACT PP 164,597 A self energizing valve for use incontrolling the flow of fluid to a fluid translating device having innerand outer members cooperating to define an annular space g :68; andbeing relatively rotatable by flowing fluid through [58] Field [177 g186 l a plurality of passageways communicating with the anl337/109 6nular space. The self energizing valve slides in a valve bore and isautomatically maintained in a first position [56] References Cited bythe pressure of fluid flowing through a fluid passage in the valvecommunicating with the passageways. The UNITED T TE PATENTS valve andbore cooperate to define a cavity and the D1etz. passage is connectableto thg cavity and the pres. a sure of the fluid in the cavity will movethe valve from 3:593:62! 7/1971 Praddauc le :11. 91 492 the 3,635,605Hall 418/32 15 Claims, 4 Drawing Figures SELF ENERGIZING VALVE MEANS FORFLUID TRANSLATING DEVICE BACKGROUND OF THE INVENTION The presentinvention relates generally to fluid translating devices of the typedisclosed in U.S. Pat. No. 3,391,609 and more particularly to animproved valve for controlling the flow of fluid in such translatingdevices.

Fluid translating devices of the type disclosed in the above mentionedpatent are generally referred to as Vane-type fluid motors. These fluidmotors generally consist of two relatively movable members that havesurfaces that cooperate to define an annular space and fluid is directedto the annular space to cause relative rotation between the members.

Normally the annular space is divided into a plurality of pulsingsections by forming the surface on one of the members of irregularcontour having lobes and depres-' sions. The pulsing sections may betermed working chambers through which fluid is directed from a pair offlowpaths defined in a valve incorporated within the fixed member of thetranslating device. The flow paths are connected to the working chambersthrough a plurality of passageways and the valve is movable within thefixed element to vary the number of passageways in communication withthe respective flow paths. With this arrangement the speed of rotationand amount of torque developed on the rotating element can be varied byvarying the communication of the respective passageways with the flowpaths.

The above mentioned patent discloses one mechanism for moving the valvemeans between positions which has found a degree of success in areaswhere the translating device is located on a position to be readilyaccessible by the operator. However, in some instances it may benecessary to actuate the valve'through some remotely controlled-mechanism and a mechanical second position through the use of anextemalcontrol pressure applied to'a cavity adjacent the valve means.While such an arrangement hasproven satisfactory for 'use in certainenvironments, some applications of fluid translating devices require thedevelopment of extremely high torque forces between the fixed and themovable element. 'The .development of high torque forces results inextensive pressurization of the entire fluid control system. Since thefluid control system includes the movable valve means as well as manyseals, all of which are under pressure, the arrangement disclosed in theabove mentioned application requires the development of extremely highcontrol pressure for moving the valvespool.

SUMMARY O THE INVENTION The present invention comtemplates controllingthe movement of the valve incorporated. into a fluid translating deviceexcul sively from the pressure of fluid developed during movement of thetranslating device. This arrangement eliminates the need for a separatev conduits.

control pressure of fluid or alternatively a mechanical linkagearrangement between the control valve and a remote operators station.

According to the invention, the control of the flow of fluid through anannular chamber defined between inner and outerrelatively movablemembers includes valve means that define flow paths to a first group ofpassageways communicating with the annular chamber, and from a secondgroup of passageways allowing the fluid to exit from the chamber. Thevalve is normally maintained in a first position by the pressure of thefluid flowing through the fluid passage to cause relative rotationbetween the two members. The valve means has a surface cooperating withone of the members to define a cavity and the present inventioncontemplates flow control means for selectively placing the fluidpassage in communication with the cavity to movethe valve spool to asecond position, thus changing the number of passageways in therespectivegroups. This arrangement will change the flow rate to and fromthe working chamber. i

More specifically, the fixed member has a bore communicating with thepassageways and with a pair .of ports at a location spaced from thepassageways. The

valve means is slidable in'the bore and cooperates therewith to dividethe fluid passage into first and second flow paths between therespective ports and the.

passageways. The bore and the end surface of the valve means cooperateto define the cavitywhile the valve means has two additional surfacesthat are in communication with the respective flow paths. The exposedsurfaces respectively in communication with the first and second flowpaths define first means cooperating with the valve means to maintainthe valve means inia first position in response to the pressure of fluidin the flow paths. v y

The flow control means for selectively placing the fluid passagein-communication with the cavity consists of a two position valvehaving-a first conduit communicating with thecavity and second and thirdconduits connecting the respective flow pathsv to the control valve withunidrectional check valves cooperating with the second and thirdconduits to accommodate flow from the flow paths to the control ;valveand prevent flow from the control valve to the second and third Thecontrol valve has a first position blocking-flow between the conduitsand exhausting the fluid from the first conduit to a reservoir andasecond position connecting the second and third conduits to the firstcon duit. With this arrangement, the check valve cooperat-- ing with theconduit having the higher. pressure fluid will be opened when the valveis in the second position and supply pressured fluid to the cavity.Proper selection of the size of the surface of the valve means in thecavity, and the surfacesrespectively in communication with the two'flowpaths will result in having the valve moved to the second position atany time the pressured fluid is transmitted to the cavity and one flowpath has ahigher pressure than the other.

All of the above can be accomplished by a simple arrangement of aminimum number of parts, all of which can readily be incorporated intoexisting fluid translating devices.

BRIEF DESCRIPTION or SEVERAL vIEws OF DRAWINGS DETAILED DESCRIPTIONWhile this invention is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail two specific embodiments, with the understanding that the presentdisclosure is to be considered 'as an exemplification of the principlesof the invention and is not intended to limit the invention to theembodiments illustrated.

' FIG. 1 of the drawings discloses a fluid translating device, generallydesignated by the reference numeral 10. The fluid translating device isillustrated as a fluid motor having a fixed element l2 and a rotatableelement 14. The fixed element 12 consists of a stator 16 non-rotatablysecured to a fixed support or load bearing member 18 through a splineconnection 20 (see FIG. 2). The second or relatively movable element 14includes an outer member 22 having spaced end plates 24 and 26 fixedlysecured to opposite ends thereof.

As more clearly shown in FIG. 2, the outer member 22 cooperates with theinner member 16 to define an annular space. The annular space is dividedinto a plurality of working chambers 28 by depressions 30 and lobes 32produced by an irregular contour on the outer peripheral surface of theinner member. While the fluid translating device has been illustrated asincluding four chambers 28 or referred to as a four lobe type, anynumber of chambers may be formed between the rotating member and thefixed member which allows for the design of 'multi-speed and directiontranslators.-

The outer rotating member has a plurality of circumferentially spacedslots 34 extending from the inner surface thereof, each of whichslidably supports a vane 36 which is spring biased into engagement withthe peripheral surface of the fixed member 16 by suitable mechanism (notshown). In addition, suitable bearings 37 are interposed between the endplates 24 and 26 and the fixed member 12. At least one of the plates 24,26 is capablelof supporting a driven element, such as a wheel securedthereto.

'In operation, pressured fluid is delivered through a 'fluid passage tothe working chambers 28 and causes a bore is defined by a sleeve 46 thatis fixedly secured into an annular chamber 54. One end of the valvemeans is closed by a cap 51 thatdefines partof the first flow path. Theperipheral portion of the valve means cooperates with the internalsurface of the bore to define a second flow path 56 leading from thesecond port 42.

plurality of axially spaced grooves 60, 62 and 64 through openings 57,58, and 59. As seen in FIG. 1, the circumferentially extending grooves60, 62 and 64 are defined on the inner surface of the stator 16 and, the

respective annular grooves 60, 62 and 64 are in corn munication with therespective chambers 28 through axially and circumferentially spacedpassageways 70, 72 and 74.

The annular grooves and cooperating passageways are separated into firstand second groups adjacent the openings 57, S8 and 59 by a peripheralflange 80 that has its outer surface in sealing engagement with thesurface of the bore 44.

An inspection of FIG. 1 reveals that the position of the valve means 48in the bore 44 will determine the number of passageways that are'incommunication with the respective flow paths. In the positionillustrated in FIG. 1, a first group of passageways 72 and 74 are incommunication with the first flow path while the second group ofpassageways are in communication with the second flow path 56. It may bestated that the flow paths and passageways cooperate to define a fluidpassage through the chambers 28. Furthermore, movement of the valvemeans 48 to the second position shown in FIG. 3 will change the numberof passageways in the respective groups described above. i

The arrangement of the elements of the valve means is such that thevalve means will automatically be in a first position when the members14 and 16 are rotated relative to each other. Assuming that pressuredfluid delivered from a pump (not shown) is connected to the port 40, thepressured fluid will flow through the first flow path 50, the openings52, the annular chamber 54 through the first group of passageways 72, 74through the chambers 28 and will be exhausted from the chambers 28through the second group of passageways70 and passageway 56 afterrotating the outer member through the cooperation with the vanes 36. Aninspection of FIG. 3 reveals that a pressurized fluid entering port 40will be acting upon the surface 81 of the end cap 51 on the remote endof sleeve 49. Thus, any pressure developed in the first flow path 50will maintain the sleeve or spool 49 and the elements connected theretoin the position shown in FIG. 3. The same will be true if thepressurized fluid is delivered to the port 42 and is exhausted throughthe port 40. In this instance the pressurized fluid will be acting onthe surface 82 of the flange and again will maintain the valve spool inthe first position shown in FIG. 3. The first surface 81 that is exposedto the pressure of the fluid in the first flow path 50 and the secondsurface exposed to the pressure of fluid in the second flow paths 56 maybe termed as first means cooperating with the valve means toautomatically maintain the valve means in a first position in responseto the flow of fluid in the fluid passage.

As was stated above, the valve is moved to a second position by flowcontrol means utilizing the fluid flowing through the fluid passage.This arrangement elimi- The opposite end of the bore communicates with ahates the need for any external source of fluid or mechanicalconnections to actuate the valve means.

Referring to FIG. 1, the bore 44 is closed at its remote end by a cover84 and cooperates with the end cap 51 on the sleeve 49 to define acavity or chamber 86. The surface 88 on the end cap 51 cooperates withthe first member to define the cavity.

The flow control means for selectively placing the fluid passage incommunication with the cavity will now be described. The flow controlmeans is illustrated in FIG. I and includes a two-position valve 90having a first conduit means in communication with the cavity 86. In theillustrated embodiment the first conduit means consists of a firstconduit 92 in communication with the cavity 86 through a tube 94extending through an opening in the closed end cap 51 of the sleeve 44with the opposite end of the tube fixedly secured to the closed end 96of the bore 54. The end 96 for the bore has a small opening 98 incommunication with the tube 94 and the conduit 92.

The flow. control means also has second conduit means connecting thecontrol valve 90 to the fluid passage including the firstand second flowpaths 50 and 56. The second conduit means consists of second and thirdconduits 100 and 102 connected to the flow paths 50 and 56. The secondand third conduits '100 and 102 respectively have unidirectional valvesin the form of flow paths 56 and 50,'in communication with the'cavity86'whenever either of the check valves'is open. Thus, any pressure offluid developed in either of the flow paths will open the associatedcheck valve and cause fluid to flow into the cavitythereby moving thevalve means to its second position shown in FIG. 1. Such a a conditionwill occur anytime there is pressurized fluid flowing-"through the fluidpassageway to rotate the outer member'relative to the inner member,because the higher pressure fluid in the fluid passage will be acting oneither surface 81' or 82'and will also be acting on surface 88 which islarger than either of the surfaces 81 'or'82-.'This must necessarily betrue since the rotation of the two members relative to each other canonly 88 is substantially greater than the surface area of either of thesurfaces 81 and 82. Preferably, the surface torque in either the forwardor reverse direction by supplying pressured fluid to either port 40 or42, the

pressure of thefluid will act over half of the area of the end on thesleeve 49 to shift the valve 48 to the right as viewed in FIG. 1. Evenif the motor is not delivering torque, both surfaces 81 and 82 will besubjected to the charging pressure of the entire system for deliveringfluid to either of the flow paths. Thus, for example, when utilizing thefluid motor for driving the wheels of a large tractor, it is customaryto maintain a predetermined pressure in the entire closed loop systemfor delivering fluid to the flow paths 50 and 56 and this pressure offluid will be acting on both of the surfaces 81 Assuming that thecontrol valve 90 is now moved to its other operative position, the flowof fluid between conduit 92 and either of conduits 100 and 102 isblocked while the first conduit 92 is placed in communication with thereservoir 110. Upon moving the control valve 90 to its first position,any pressure of fluid in the fluid passage between ports 40 and '42 willforce the fluid from cavity 86 into the reservoir 110. This will causethe valve means 48 to move to its position shown in FIG. 3.

While not specifically limited to any configuration, it is desirable toproperly size the surfaces 81, 82 and 88. Thus, the surfaces 81 and 82define areas which are substantially equal to each other while the thirdsurface and 82 to cause the valve 48 to move to the first position shownin FIG. 3 whenever the cavity 86 is vented.

With the above construction and arrangement of parts, it will beappreciated that there will always be fluid under pressure in one of theflow paths to maintain the valve means in the first position. However,if the motor is untorqued, there will be no difference between thepressures in the fluid passages and the pressure of fluid on thesurfaces 81, 82 and 88 will be equal.

Therefore, the valve will not move from its first position to the secondposition until the pressure of fluid to either port 40 or 42 isincreased. If such a delay in moving the valve 48 is not desired, aspring may be placed in the cavity 86, as shown in FIG. 4, and act onthe closed end cap 51 to move the valve 48 to the left whenever thevalve is hydraulically balanced. Alternatively, the size of the surfacearea 88 may be increased to be greater than the combined area of thesurfaces 81,82. 7 p

If there is no pressurized fluid in the system when the fluid motor isuntorqued, the spring 86 would only have I to move the valve 48 to'itssecond position. Preferably the spring would deliver about half as muchforce as the charging pressure acting over the entire area-of the remote end of the valve.

An alternate construction would be to connectconduit 108 into the fluiddelivery system for the ports 40 and 42. With such an arrangement, thevalve 48 could always be urged to the right whenever torque wasdelivered by the motor and would be balanced when the motor isuntorqued.

The present arrangement insures that there is always a sufficientpressure of fluid to. overcome the pressure developed in the variousseals between the valve and the bore since the control pressure to thecavity is always equal to the pressure delivered through the flow paths.

What is claimed is:

l. lnafluid translating device having inner and outer memberscooperating to define an annular space and being relatively rotatable;means defining a plurality of passageways communicating with saidannular space;

and means for directing fluid through said passageways to producerelative rotation of said members comprising: means defining a borecommunicating with said passageways, said bore having first and secondports communicating therewith at a location spaced from passageways;valve means slidable in said bore and cooperating with said bore toproduce a fluid passage defining first and second flow paths betweenrespective ports and said passageways; and moving means for moving saidvalve means, said moving means including first means defining surfaceson said valve means exposed to the fluid pressure in said fluid passageto maintain said valve means in a first position in response to thepressure of fluid in said flow paths; and flow control means cooperatingwith said flow paths to selectively place said flow paths incommunication with one end of said valve means to overcome said firstmeans to move said valve means to a second position with the fluidflowing in the fluid passage.

2. A fluid translating device as defined in claim 1, in which said valvemeans includes a first surface exposed to the pressure of fluid in oneof said flow paths, a second surface exposed to the pressure of fluid inthe other of said flow paths and a third surface on said end of saidvalve means, said first and second surfaces being arranged to definesaid first means to move said valve means to said first position whenthe fluid in either of said paths is pressurized, said third surfacebeing opposed to said first and second surfaces to move said valve meansto said second position when said flow paths are in communicationtherewith.

3. A fluid translating device as defined in claim 1, in which said valvemeans includes a sleeve closed at one end and having its opposite end incommunication with one of said ports, said sleeve having a peripheralflange,

engaging said bore with an annular surface of said flange exposed to thefluidin the other of said paths,

.the opposite surface of said closed end being adapted to be exposed tothe fluid in said flow paths.

4. A-fluid translating device as defined in claim 1, in which said valvemeans and said bore cooperate to define a cavity with said control flowmeans including a conduit communicating with said cavity and a controlvalve actuatable to supply pressurized fluid from said' flow paths tosaid cavity.

5. A fluid translating device as defined in claim 4, further includingsecond and third conduits connecting said flow paths to said controlvalve and unidirectional valves cooperating with saidsecond and thirdconduits accommodatingflow from said flow paths to said control valveand preventing flow from said control valve to said second and thirdconduits; said control valve having a first position blocking flowbetween said conduits and exhausting the fluid from said first conduitand a second position connecting said second and third conduits to saidfirst conduit. 7

. 6.'A fluid translating device as defined in claim 4, in which saidvalve means includes a sleeve having a closed end cooperating with saidbore to define said cavity, and an open end communicating with saidfirst port, said sleeve having a peripheral flange having a surface incommunication with said second port, said flange being on opposite sidesof at least one of said passageways when said valve means is in therespective positions.

7. A fluid translating device as defined in claim 4, in which said valvemeans has a first surface exposed to the fluid in one of said paths anda second surface exposed to the fluid in the other of said paths withthe areas of said surface being substantially equal to each other, andin which said valve means has a third surface having an areasubstantially greater than either of said first and second 'surfaces.

8. A fluid translating device as defined in claim 7, further includingbiasing means in said cavity and acting on said sleeve for moving saidsleeve to said second position when the pressure of fluid in said flowpaths and said cavity is substantially balanced.

9. A fluid translating device as defined in claim 7, in which said thirdsurface area is substantially equal to the combined area of said firstand second surface areas.

10. In a fluid translating device including inner and outer memberscooperating to define a working chamber having a plurality ofpassageways in communication therewith with the flow of fluid throughsaid chamber causing relative rotation between said members; meansdefining a fluid passage through a first group of said passageways, saidchamber and a second group of passageways, said means including valvemeans automatically maintained in a first position by the pressure ofthe fluid flowing through said fluid passage and having a surfacecooperating with one of said members to define acavity; and flow controlmeans for selectively placing said fluid passage in communication withsaid cavity to move said valve means to a second position and change thenumber of passageways in said first and second groups.

11. A fluid translating device as defined in claim 10, in which saidflow control means includes a control valve having first conduit meansconnecting said valve to said cavity and second conduit means connectingsaid valve to said fluid passage, said valve having a first positionblocking flow between said conduit means and a second positionaccommodating flow between said conduit means. I

12. A fluid translating device as defined in claim 11, in which saidflow control means further includes a conduit connecting said valve to areservoir with said first conduit means in communication with saidconduit means in said cavity has an area substantially equal to thecombined area of the surfaces exposed to said flow paths and the areasof the surfaces exposed to the respective flow paths are approximatelyequal to each other.

14. A fluid translating device as defined in claim 13, further includinga spring in said cavity and acting on said surface in said cavity tomove said valve means to said second position when said flow controlmeans places-said fluid passage in communication with said cavity and nopressure difference exists.

15. A fluid translating device as defined in claim 13, in which saidflow control means includes a control valve; a first conduit connectingsaid valve to said cavity; second and third conduits connecting saidflow and a second position accommodating such flow.

l i i t

1. In a fluid translating device having inner and outer members cooperating to define an annular space and being relatively rotatable; means defining a plurality of passageways communicating with said annular space; and means for directing fluid through said passageways to produce relative rotation of said members comprising: means defining a bore communicating with said passageways, said bore having first and second ports communicating therewith at a location spaced from passageways; valve means slidable in said bore and cooperating with said bore to produce a fluid passage defining first and second flow paths between respective ports and said passageways; and moving means for moving said valve means, said moving means including first means defining surfaces on said valve means exposed to the fluid pressure in said fluid passage to maintain said valve means in a first position in response to the pressure of fluid in said flow paths; and flow control means cooperating with said flow paths to selectively place said flow paths in communication with one end of said valve means to overcome said first means to move said valve means to a second position with the fluid flowing in the fluid passage.
 2. A fluid translating device as defined in claim 1, in which said valve means includes a first surface exposed to the pressure of fluid in one of said flow paths, a second surface exposed to the pressure of fluid in the other of said flow paths and a third surface on said end of said valve means, said first and second surfaces being arranged to define said first means to move said valve means to said first position when the fluid in either of said paths is pressurized, said third surface being opposed to said first and second surfaces to move said valve means to said second position when said flow paths are in communication therewith.
 3. A fluid translating device as defined in claim 1, in which said valve means includes a sleeve closed at one end and having its opposite end in communication with one of said ports, said sleeve having a peripheral flange engaging said bore with an annular surface of said flange exposed to the fluid in the other of said paths, the opposite surface of said closed end being adapted to be exposed to the fluid in said flow paths.
 4. A fluid translating device as defined in claim 1, in which said valve means and said bore cooperate to define a cavity with said control flow means including a conduit communicating with said cavity and a control valve actuatable to supply pressurized fluid from said flow paths to said cavity.
 5. A fluid translating device as defined in claim 4, further including second and third conduits connecting said flow paths to said control valve and unidirectional valves cooperating with said second and third condUits accommodating flow from said flow paths to said control valve and preventing flow from said control valve to said second and third conduits; said control valve having a first position blocking flow between said conduits and exhausting the fluid from said first conduit and a second position connecting said second and third conduits to said first conduit.
 6. A fluid translating device as defined in claim 4, in which said valve means includes a sleeve having a closed end cooperating with said bore to define said cavity, and an open end communicating with said first port, said sleeve having a peripheral flange having a surface in communication with said second port, said flange being on opposite sides of at least one of said passageways when said valve means is in the respective positions.
 7. A fluid translating device as defined in claim 4, in which said valve means has a first surface exposed to the fluid in one of said paths and a second surface exposed to the fluid in the other of said paths with the areas of said surface being substantially equal to each other, and in which said valve means has a third surface having an area substantially greater than either of said first and second surfaces.
 8. A fluid translating device as defined in claim 7, further including biasing means in said cavity and acting on said sleeve for moving said sleeve to said second position when the pressure of fluid in said flow paths and said cavity is substantially balanced.
 9. A fluid translating device as defined in claim 7, in which said third surface area is substantially equal to the combined area of said first and second surface areas.
 10. In a fluid translating device including inner and outer members cooperating to define a working chamber having a plurality of passageways in communication therewith with the flow of fluid through said chamber causing relative rotation between said members; means defining a fluid passage through a first group of said passageways, said chamber and a second group of passageways, said means including valve means automatically maintained in a first position by the pressure of the fluid flowing through said fluid passage and having a surface cooperating with one of said members to define a cavity; and flow control means for selectively placing said fluid passage in communication with said cavity to move said valve means to a second position and change the number of passageways in said first and second groups.
 11. A fluid translating device as defined in claim 10, in which said flow control means includes a control valve having first conduit means connecting said valve to said cavity and second conduit means connecting said valve to said fluid passage, said valve having a first position blocking flow between said conduit means and a second position accommodating flow between said conduit means.
 12. A fluid translating device as defined in claim 11, in which said flow control means further includes a conduit connecting said valve to a reservoir with said first conduit means in communication with said conduit when said valve is in the first position.
 13. A fluid translating device as defined in claim 10, in which said valve means divides said fluid passage into first and second flow paths and has respective surfaces exposed to the pressure of fluid in the respective flow paths and in which said surface of said valve means in said cavity has an area substantially equal to the combined area of the surfaces exposed to said flow paths and the areas of the surfaces exposed to the respective flow paths are approximately equal to each other.
 14. A fluid translating device as defined in claim 13, further including a spring in said cavity and acting on said surface in said cavity to move said valve means to said second position when said flow control means places said fluid passage in communication with said cavity and no pressure difference exists.
 15. A fluid translating device as defined in claim 13, in which said flow control means incluDes a control valve; a first conduit connecting said valve to said cavity; second and third conduits connecting said flow paths to said valve and each having a check valve preventing flow from the control valve to the flow paths, said control valve having a first position blocking flow from the second and third conduits to the first conduit and a second position accommodating such flow. 